Pure gold (Au) is a soft yellow high-plasticity metal that can be forged in 0.1 μm (100 nm) thick forms and stretched out in a wire with linear density up to 2.0 mg/m.
Gold melting temperature reaches 1064.18° C. (1337.33K), boiling point−T (temperature)=2856° C. (3129K).
Density of liquid gold is less than that of solid gold and is equal to 17 g/cm3 at the melting temperature.
Liquid gold is quite volatile, it actively vapors out long before the boiling point is reached.
Gold is a very heavy metal, density of pure gold is equal to 19.32 g/cm3 
Gold is one of the most inert metals, under normal conditions it does not interact with majority of acids and does not form oxides, that is why gold is a precious metal.
Current world reserves of gold are distributed as follows:
about 10% is used for industrial products, the rest is distributed approximately in equal parts between centralized reserves (mainly in the form of chemically pure gold bars) and individuals in the form of gold bars and jewelry.
Gold is inferior to majority of platinoids by its chemical resistance and mechanical reliability. However, gold is irreplaceable as a material for electrical contacts.
Therefore, gold conductors and electroplated gold coating of contact surfaces, connectors, printed boards are widely used in microelectronics.
Gold is used as a target in atomic researches and as coating for mirrors operating in far infrared band.
Gold is also widely used in dentistry, pharmacology and registered as a food supplement E175.
Therefore, there was high demand for gold at all times.
However, there is a significant problem associated not only with the recovery of high-purity gold, but also with the recovery of gold from the gold-bearing ore as all gold fields differ from each other by their chemical composition and impurities. Therefore, almost each gold field requires individual technology to process the gold-bearing ore.
The existing pure gold recovery technologies are mainly associated with the dissolution of the gold-bearing ore in various acids and its further recovery from gold solutions, for instance, gold dissolution in aqua regia, i.e. a mixture of nitric and hydrochloric acids.
However, these methods do not enable recovery of high-purity 999.9 fine gold.
The 999.9 fine gold corresponds to a gold chemical purity of 99.99%.
Gold may also be recovered by a chlorination method.
All processes of gold recovery from the gold-bearing ore by the chlorination method described in patents are practically identical, for instance, the Soviet patent SU770220 A1, published on Jul. 10, 1999, “A Method of Processing a Precious Metal-Bearing Material by Chlorination”, suggesting passing through gaseous chlorine in molten alkali-metal chlorides at T=620-750° C. In order to accelerate the process rate and increase the chlorination degree, the base material is immersed to the depth of 0.1-3 mm prior to chlorination, and gaseous chlorine is supplied between two phases “base material-molten material”, with further removal of resulted chlorides of precious metals by shaking and stirring of the molten material.
Disadvantage of this method is that many impurities, such as iron, molybdenum, tungsten, vanadium, etc., are chlorinated at T=620-750° C. as well that leads to the contamination of chlorides of precious metals, and such impurities are difficult to remove in future processes.
There is a method of gold chlorination in a molten mass at T=1423K, (Russian patent RU 2181780 C2 published on Apr. 27, 2002), which suggest supplying gaseous chlorine through graphite pipes in the preliminary melted material at T=1423K.
In such a way, the resulted chlorides of impurity metals (iron, zinc, lead, etc.) are distilled off and trapped in electrostatic condensers.
Upon the distillation of the main mass of impurities, cupric and iron chlorides are removed from the molten mass, and recovered gold is poured in casting molds, thus producing commercial bars with gold content of at least 99.5% and silver—0.35%.
Disadvantages of this method are high energy consumption, complexity of equipment used due to high temperatures required for chlorine operations and strict requirements to environmental safety.
In addition, it is impossible to recover high purity gold (999.9 fine).
All these methods are highly expensive and environmentally unsustainable, they require multiple operations to purify impurities that causes many problems in such industries.
Therefore, there is the need to develop new cost effective, environmentally friendly and safe technologies.